INCREASED UNIFORMITY AND THERMAL-STABILITY OF COSI2 THIN-FILMS BY TI CAPPING

A thin (1-3 nm) Ti layer is shown to improve the uniformity and the thermal stability of CoSi2 layers grown on Si substrates. The beneficial effect of the Ti(TiN) cap is demonstrated for a variety of CoSi2 layers, including Ti-interlayer mediated epitaxial (TIME) CoSi2/Si(100), polycrystalline CoSi2/Si(100), and CoSi2/polycrystalline Si. The increased uniformity and stability of the silicide layers are speculated to result from reduced surface and interface diffusion during nitrogen and/or vacuum anneals. In the case of TIME CoSi2/Si(100), both the use of a Ti cap and the removal of a metastable Ti4CO4Si7 overlayer prior to high-temperature anneals are found important for the fabrication of uniform, single-crystal layers. (C) 1995 American Institute of Physics.